Can’t install the plugin

I purchased this plugin this morning and it worked perfectly with the first wordpress site I had ( tayibs.com) then I tried using the downloaded zip file for my second site and it didn't work. So i ended purchasing another copy ( thinking that each code works for only one site). So I bought a second copy and it still can't be downloaded ( I get an internal error message) and it is driving me crazy. Can someone assist with it. I can create a temporary admin and password for that matter. thanks